Urinary kallikrein excretion in patients with primary aldosteronism: differentiation of adrenal adenoma from idiopathic adrenal hyperplasia.

Following 7 days on a low sodium diet, a regular sodium diet or a high sodium diet each, urine samples were collected from 37 subjects in the final days of each sodium treatment. Urinary kallikrein excretion was determined in 9 patients with primary aldosteronism, 15 normal subjects and 13 patients with essential hypertension. Urinary aldosterone excretion, plasma renin activity (PRA), urinary sodium excretion, urinary potassium excretion and p-aminohippuric acid clearance were also determined on the same days. Levels of urinary kallikrein excretion in patients with primary aldosteronism due to aldosterone-producing adenoma (APA) were greater (p less than 0.05 to p less than 0.001) than those in patients with primary aldosteronism due to idiopathic adrenal hyperplasia (IHA) under any sodium diet. Other examined variables were of limited value in differentiating patients with APA from those with IHA. Urinary kallikrein excretion, urinary excretion of electrolyte, urinary aldosterone excretion, PRA and PAH clearance were similar in normal subjects and patients with essential hypertension. It appears reasonable to conclude from these data that urinary kallikrein does not play an important role in the pathogenesis of essential hypertension, and elevated urinary kallikrein excretion in patients with primary aldosteronism due to APA can be used for biochemical differentiation from those with IHA.